Vehicles which include opening portions positioned at rear end portions of the vehicles that are opened and closed by back doors have been widely used, facilitating access to cargo spaces positioned in back of rear seats of the vehicles.
Such a back door of a vehicle is a hatch back door having an upper portion turnably attached to a vehicle upper structure via a pair of right and left hinges, and vertically turned around the hinges to open and close. The back door uses a structure in which a damper stay is bridged between the back door and a body to reduce an operation force for opening the back door and to maintain the opening state of the back door (e.g., see JP 2009-234417 A).
Furthermore, in recent years, many vehicle doors made of resin have been used. The doors made of resin have a reduced weight but ensuring rigidity is difficult as compared with doors made from steel plate. For this reason, a structure has been proposed to mount a metal reinforcing member in a hollow space defined by a resin inner panel and a resin outer panel (e.g., see JP 5846036 B). As such a structure, a configuration to fix a metal reinforcing member to a resin inner panel with an adhesive is known (e.g., see JP 2011-136606 A).